Setting and releasing apparatus for sidewall anchor

ABSTRACT

In accordance with an illustrative embodiment of the present invention as disclosed herein, an open hole sidewall anchor used in drill stem testing operations and including normally retracted slips that are set and released in response to downward and upward movement, respectively, or an associated expander, is provided with a spring loaded drive sleeve connected to the expander. A mandrel that is movable upwardly and downwardly as well as rotationally within a housing can be rotated in the lower position to cause a feed mechanism to advance the drive sleeve and expander downwardly to set the slips. Upward movement of the mandrel allows the feed mechanism to disengage, so that the spring shifts the drive sleeve and the expander upwardly to cause the slips to retract.

United States Patent Mullins l l SETTING ANl) RELEASING APPARATUS FOR SIDEWALL ANCHOR [75] Inventor: Albert A. Mullins. Boling. Tex.

(73] Assignee: Schlumberger Technology Corporation, New York. NY.

22 Filed: July 17. 1974 211 Appl. No.: 489,346

[52] U.S. Cl. 166/217; 166/139; 166/237 [Sll lnt.Cl ..E2lb23/00;E2lb 33/12 [58] Field of Search 166/139. 217, 237

[56] References Cited UNITED STATES PATENTS 2.498.791 2/l95U Clark n l66/l39 2,998.073 8/l96l Clark. Jr. et al is l66/l39 3,289.766 2/!966 Bigclow l66/l39 June 17, 1975 Primary Examinerlames A. Leppink Attorney, Agent, or FirmDavid L. Moseley; William R. Sherman; Stewart F. Moore [57] ABSTRACT In accordance with an illustrative embodiment of the present invention as disclosed herein, an open hole sidewall anchor used in drill stem testing operations and including normally retracted slips that are set and released in response to downward and upward movement, respectively, or an associated expander, is provided with a spring loaded drive sleeve connected to the expander. A mandrel that is movable upwardly and downwardly as well as rotationally within a housing can be rotated in the lower position to cause a feed mechanism to advance the drive sleeve and expander downwardly to set the slips. Upward movement of the mandrel allows the feed mechanism to dis engage, so that the spring shifts the drive sleeve and the expander upwardly to cause the slips to retract.

14 Claims, 11 Drawing Figures PATENTEDJUH 17 m :a 59.7 5 0 SHEET 1 FIG? PATENTEIJJUN 17 ms SHEET 3 FIG. 5 72 PATENTEDJUH 17 I975 SHEE? FIG. 10

SETTING AND RELEASING APPARATUS FOR SIDEWALL ANCHOR This invention relates generally to well tools, and particularly to a new and improved sidewall anchor apparatus that can be repetitively set and released in a simple and reliable manner in a well conduit.

A well operation such as the drill stem test normally is conducted in a newly drilled, uncased section of a well bore. When the test is not conducted adjacent the well bottom, it becomes necessary to anchor the tools against longitudinal movement by expansible and retractible slip elements which grip the wall of the borehole. Moreover, it may be desirable to conduct a test of each of several separate intervals of the well bore in a single run of the test tools into the well, requiring an anchor apparatus capable of being repetitively set and released to provide support for the equipment at various elevations in the borehole.

It is an object of the present invention to provide a new and improved anchor apparatus that can be set and then released in the well in a simple and reliable manner requiring only minimum manipulation of the drill stem or pipe string extending upwardly to the surface.

Another object of the present invention is to provide a new and improved open hole anchor apparatus that can he set in response to rotation of the pipe string, and then released in response to only vertical upward movement thereof.

Yet another object of the present invention is to provide a new and improved well tool anchor apparatus of the type described, wherein the apparatus, when released from its anchored condition by vertical upward movement of the pipe string, is automatically reconditioned for additional setting operations without further.

manipulation.

These and other objects are attained in accordance with the concepts of the present invention through the provision of an anchor apparatus including a housing that carries normally retracted means, such as toothed slip elements, that are shifted outwardly into anchoring contact with a well bore wall by an expander that is movable downwardly within the housing member to expand the slip members, and upwardly therein effect a retraction of the slip members. A mandrel that is coupled on one end to the pipe string extends into the housing member and is movable rotationally as well as longitudinally with respect thereto. Means are provided for feeding the expander means downwardly within the housing in response to rotation of the mandrel to cause expansion of the slip members into anchoring contact, and for disabling the feeding means in response to upward movement of the mandrel. When the feeding means in disabled, the expander is shifted automatically to its initial upper position where the slip elements are retracted, and downward movement of the mandrel relative to the housing will again activate the feeding means so that the anchor apparatus can be set repetitively in the well bore as desired.

The present invention has other objects and advantages which will become more clearly apparent in connection with the following detailed description ofa preferred embodiment, taken in conjunction with the appended drawings in which:

FIG. I is a schematic view of a borehole with a packer and associated testing equipment positioned and anchored therein;

FIGS. 2A and 2B are longitudinal sectional views, with portions in side elevation, of an anchor apparatus incorporating the principles of the present invention;

FIG. 3 is a side sectional view of one of the slip members of the anchor apparatus;

FIG. 4 is a rear view of the slip member of FIG. 3;

FIG. 5 is a side sectional view of the other slip member of the anchor apparatus;

FIG. 6 is a bottom view of the slip member of FIG.

FIG. 7 is a side view of the expander member that is utilized to expand and retract the slip members;

FIG. 8 is a cross-section taken on line 8-8 of FIG. 2A;

FIG. 9 is an isometric exploded view of the drive sleeve and the upper end portion of the setting sleeve; and

FIG. 10 is a right-side" sectional view of an alternative drive sleeve embodiment.

Referring initially to FIG. 1, a schematically illustrated assemblage of drill stem testing tools is shown suspended in well bore 10 on a pipe string 11. The tools as disclosed in further detail in copending application Ser. No. 410,944, assigned to the assignee of this invention, will normally include a straddle packer assembly capable of sealing off and isolating the interval of the borehole that is to be tested, and may comprise, for example, spaced apart, inflatable elements 12 and 13 that can be inflated and expanded outwardly into sealing contact with the surrounding well bore wall. A pump assesmbly 14 is used to supply fluid under pressure to effect expansion of the packing elements in response to appropriate manipulation of the pipe string 11, and a valve 15 can be operated at the end of the test in order to deflate the packer elements and to equalize pressures. A tester assembly 16 also is actuated by movement of the pipe string 11 and includes valve elements which open and close a test passage extending through the tools from test ports 17 located between the packing elements 12 and 13 upwardly into the pipe string II so that the isolated interval of the borehole can be permitted to flow for a period of time and then can be shut-in to enable recordal of pressure build-up data by a typical pressure recorder 18. A sample chamber in the tester assembly 16 functions to trap the last flowing portion of the formation fluids for subsequent inspection and analysis. A reverse circulating valve 19 can be operated at the end of a test in such a manner that formation fluids recovered in the pipe string 11 can be cleared to the surface before the equipment is withdrawn from the borehole.

The lower end of the string of tools is constituted by an anchor assebmly 25 that can be repetitively set and released in accordance with the principles of the pres ent invention. The anchor assembly 25 is overall arrangement includes a mandrel 26 that is telescopically and rotatably received within an elongated housing 27. The housing 27 carries drag means such as bow spring 28 that engage the well bore wall to inhibit movement of the housing therein, and oppositely facing slip elements 29 and 30 that are adapted to be extended by an associated expander from retracted positions to extended positions in anchoring contact with the well bore wall as shown. Such extension as well as release of the slip elements 29 and 30 is accomplished in response to movement of the mandrel 26 relative to the housing 27 through appropriate manipulation of the pipe string 11 at the surfaces as will be more fully described herebelow.

As shown in enlarged detail in FIGS. 2A and 2B, the elongated tubular housing 27 may be constituted by several interconnected sections including an anchor sub 31 and a drag sleeve assembly 32. The drag sleeve assembly 32 includes upper and lower connector subs 33 and 34, each of which carries a retainer sleeve 35, 36 fixedly attached thereto. The lower end portion of each bow spring 28 is received within the lower retainer sleeve 36, whereas the upper end portion of each spring is received within the upper retainer sleeve 35. The respective portions extend through vertical slots 37 and 38 formed in outwardly projecting shoulders 39 and 40 on the drag sleeve 32 and are otherwise loosely coupled within the retainers for limited vertical movement as the bow springs 28 flex laterally to accomodate various well bore diameters. The upper connector sub 33 carries a seal cap 42 that has an elastomer spline wiper ring 43 fixed internally thereof. A segmented spacer collar 44 is interfitted around the lower connector sub 34 and is bolted together by suitable means to provide for ease of assembly and disassembly of the various components. When the mandrel 26 is completely telescoped within the housing 27, a shoulder 45 engages the cap 42 to limit upward movement of the housing relatively along the mandrel.

The anchor sub 31 that forms the lower portion of the elongated housing 27 has two oppositely disposed side openings or windows 46 and 47 ofa generally rectangular configuration, each of which is sized to receive a slip member 29 or 30. The slip members, shown in retracted position in FIG. 2B, each have downwardly facing wickers or teeth 50 on their outer peripheries that are adapted to bite into and grip the wall of the borehole when the slips are shifted outwardly to thus anchor the assembly against downward movement. The lower end of the sub 31 is closed by a bottom plug 51 having a plurality of radial ports 52 through which well fluids can enter into the interior spaces of the toolv In order to prohibit rocks, chips or other debris from coming in, however, discshaped filter screens 53 can be provided.

The slip members 29 and 30 have respective inner inclined surfaces which are engaged by the respective outer inclined surfaces of an expander member 54 which is movable vertically within the sub 31 from an upper position, as shown, where the skips are retracted, to a lower position where they are shifted laterally outwardly through the windows 46 and 47. To provide for a uniquely wide range of anchoring diameters, a rear portion of one slip member 30 is provided with a cavity that is adapted to receive a rear portion of the other slip member 29 when the members are in retracted position. In this manner, the rear portions of each slip member overlap one another in such position, or, in other words, the inclined expander surfaces thereof extend beyond the center line of the anchor sub 31. Accordingly, as the expander member 54 is advanced downwardly from its uppermost position as shown in FIG. 2B, the slip elements 29 and 30 can be extended laterally outwardly by a significantly greater amount than was heretofore possible while maintaining adequate contact area between the expander member and the slip members to properly support them in contact with the well bore wall. Moreover, a length of contact can be maintained adequate to prevent binding of the dovetail spline and groove couplings between the expander member and the respective slip members as will be described more fully below. The details of the unique slip and expander assembly form no part of the present invention but are disclosed and claimed in application Ser. No. 489,345, Nutter, filed concurrently herewith and assigned to the assignee of this invention.

As shown in side section in FIG. 3 and in rear view in FIG. 4, the recessed slip member 30 has a rectangular cavity 58 formed in the rear thereof, with the inner wall 59 of the cavity being inclined with respect to vertical by an angle of about 15. A dovetail" spline groove 60 is provided along the rear face of the slip element 30 with the bottom surface 61 of the groove intersecting the rear wall 59 of the cavity 58 at approximately the midportion of the slip body. Side walls 62 and 63 of the groove 60 are inclined outwardly in a typical manner, whereby additional bottom surfaces 64 and 65 extend along either side of the cavity 58 over the lower portion of the slip body. The bottom surface 61 and the surfaces 64 and 65 provide ample bearing area for the expander 54 in the expanded position of the slip member 30. The opposite slip member 29 as shown in FIG. section in lFIG. 5 and in bottom view in FIG. 6, has an outwardly projecting portion 68 to the rear thereof with a transverse dimension sized to fit within the cavity 58 of the recessed slip member 30. A dovetail spline rib 69 extends for the full length of the back of the slip member 29, and has inwardly inclined side walls 70 formed in a typical manner. The outer wall surface 70 of the spline rib 69 provides an expander contact surface with ample area. The rearwardly facing walls 71 and 72 extending to either side of the splined portion 68 are appropriately shaped and arranged to interfit with the wall surfaces 73 and 74 of the recessed slip member 30 in the retracted position.

The expander member 54 that coacts with the slip members 29 and 30 to cause expansion and retraction thereof, is shown in cross-section in FIG. 2B and in side view in FIG. 7. The reduced upper neck portion 76 is appropriately threaded internally for connection to a setting sleeve 77, and externally for connection to an adjusting sleeve 88. An intermediate portion 78 of the expander member 54 is generally tubular in form. The lower end portion 79 of the expander 54 is generally wedge or spade-shaped with exterior flat wall surfaces 80 and 81 that incline downwardly and inwardly to an apexv One side of the lower portion 79 is provided with a dovetail spline rib 82 that slidably engages the spline groove 60 in the recessed slip member 30, whereas the other side has a spline groove 83 that slidably engages the spline rib 69 on the opposite slip member 29. Vertically extending keyways 84 and 85 are provided in the tubular portion 78 of the expander 54 and are engaged by longitudinal keys (not shown) carried on the inner wall of the anchor sub 31 to prevent relative rotation. As previously mentioned, the slidable spline connections between the slip members 29 and 30 and the expander 54 cause the slips to be positively retracted to the positions shown in FIG. 28 when the expander is in the upper position within the sub 31, whereas the respective coengaged expander surfaces cause outward shifting of the slips to expanded positions in response to downward movement of the expander relative to the anchor sub.

Referring again to FIGS. 2A and 2B, the expander member 54 is connected by threads to the setting sleeve 77 which extends upwardly within, the housing 27 and has an internally threaded section 89 at its upper end. The outer periphery of the section 89 is provided with longitudinally extending spline grooves 90 that mesh with inwardly directed spline ribs 91 on the drag sleeve 32 to prevent relative rotation therebetween. The body member or mandrel 26 extends downwardly into the housing 27 and within the sleeve 77 and is provided with a threaded collar 92 at its upper end for connecting the mandrel to the tools thereabove. The mandrel 26 is provided with longitudinally extending splines 93 running throughout a majority of its length and is reduced in diameter along its lower portion 94.

A drive sleeve 96 is slidable relatively along the mandrel 26 and is cut longitudinally at circumferentially spaced points from its lower end to provide a plurality of circumferentially spaced, laterally flexible fingers 97, each of which has an enlarged head portion 98 at its lower end as shown in side view in FIG. 2A and in section in FIG. 8. The head portions 98 each have external left-hand threads 99 that mesh with the internal threads 100 on the setting sleeve section 89, and have an arcuate dimension sized to fit into the grooves between the spline ribs 93 on the mandrel 26. The upper end portion 103 of the drive member 96 is circumferentially continuous and also is provided with internal spline grooves 104 in mesh with the mandrel ribs 93, whereas its external configuration is provided by an outwardly directed shoulder 105 that is located below an inwardly directed stop ring 106 on the connector sub 33.

The transverse dimension of the bottom surface 101 between spline ribs 93 and the cross-sectional thickness of the head portions 98 are sized such that the threads 99 on the head portions are locked in engagement with the threads 100 on the setting sleeve 77 when the mandrel 26 is telescoped downwardly within the housing 27. However when the mandrel 26 is elevated with respect to the housing 27 by an amount sufficient to dispose the reduced diameter lower section 94 thereof adjacent the head portions 98, the fingers 97 and the head portions 98 can resile inwardly by an amount sufficient to disengage the threads 99 and 100 and permit the setting sleeve 77 to be forced in an upward direction with respect to the housing 27 by a coil compression spring 110 that surrounds the sleeve 77 and reacts between a downwardly facing shoulder surface 111 on the sleeve 77 and an upwardly facing shoulder surface 112 on the lower connector sub 34.

ln order to assure that the threads 99 on the head portions 98 are properly meshed with the threads 100 on the setting sleeve section 89 when the latter is in the upper position, a timing mechanism is provided as shown in FIGS. 2A and 9. This mechanism is constituted by a cam ring 115 that abuts against the shoulder 105 and is fixed to the drive sleeve 103 by a lock screw 116 or the like. The lower face 117 of the cam ring 115 is machined on a helix with the same lead as the threads 99 on the head protions 98. The upper end surface 118 of the setting sleeve section 89 also is machined on the same helix, so that when the coil spring 110 shifts the setting sleeve 77 upwardly within the housing 27 as described above, the opposed end faces 117 and 118 come into abutting engagement with the section 89 in a longitudinal position for the threads 99 and to mesh properly for any angular orientation of the section 89.

In operation, the string of test tools is lowered into the well bore 10 on the pipe string 11 and positioned such that the packer elements 12 and 13 straddle the interval of the well to be tested. During lowering, of course the elements 12 and 13 are deflated, and the slip elements 29 and 30 are in retracted positions. The bow springs 28 slide downwardly along the borehole wall in frictional engagement therewith and tend to support the elongated housing 27 such that the mandrel 26 is fully telescoped therewithin. In order to actuate the pump assembly 14 in response to upward and downward movement of the pipe string 11, it is necessary to anchor against downward movement, which is accomplished in the following manner. The pipe string 11 is rotated to the right, causing the entire assemblage of tools above the anchor assembly 25 to rotate also. The mandrel 26 is thereby rotated with respect to the housing 27 which is held stationary by frictional engagement of the drag springs 28 with the well bore wall, causing the drive member 96, which rotates with the mandrel, to feed the setting sleeve 77 downwardly with respect to the housing 27. The corresponding downward movement of the expander 54 causes the slip members 29 and 30 to be shifted laterally outwardly through the windows 46 and 47 until their teeth 50 come into gripping contact with the wall of the borehole. As the setting sleeve 77 is advanced downwardly, coil spring is compressed and loaded and thus yieldably urges the setting sleeve upwardly or in the direction to retract the slip elements. When the mandrel 26 has been rotated eight to ten revolutions with respect to the housing 27, the slip elements 48 and 49 will normally have engaged the well bore wall, which can be confirmed at the surface by lowering the pipe string 11 and observing on the rig weight indicator that the an chor assembly 25 is supporting a load.

Due to the initial vertical spacing between the caps 51' and 34' on the subs 31 and 34, respectively, the sub 31 can move downwardly with the expander 54 to a limited extent as the slips 29 and 30 are set. This feature enables pipe weight to be applied directly to the expander via the sleeves 96 and 77 if it is desired to increase the purchase of the slips in this manner.

The anchor assembly 25 prevents downward movement of the tools as the pump assembly 14 is actuated in order to inflate the packing elements 12 and 13 and thereby isolate the formation interval that is to be tested. With the elements inflated, the tester valve assembly 16 is operated to alternately flow and shut-in the formation to enable the pressure recorder 18 to instrumentally record the resulting data. When the data has been recorded and it is desired to terminate the test, the valve assembly 15 is operated to cause pressure equalization and deflation of the packer elements 12 and 13. The anchor assembly 25 is released by sim ply picking straight upwardly on the pipe string 11.

It will be recognized that when the mandrel 26 is moved upwardly relative to the housing 27 by an amount sufficient to position the reduced diameter lower section 94 thereof behind the head portions 98 of the drive sleeve 96, the head portions are unsupported and are free to resile inwardly. Thus the com pressed coil spring 110 forces the drive sleeve 77 upwardly within the housing 27 to its original position,

with the teeth 100 and 99 ratcheting past each other due to camming action of the inclined side wall of the threads. The setting sleeve 77 of course moves the expander member 54 to its upper position, whereby the respective spline couplings 60, 82 and 69, 83 cam the slip elements 29 and 30 inwardly to their fully retracted positions. so that the anchor assembly can be moved longitudinally through the well bore with the tool string thereabove.

The anchor assembly 25 can be set repetitively in the well bore by merely lowering the mandrel 26 within the housing 27 to position the enlarged diameter upper spline section behind the head portions 98 of the drive sleeve 96 to thereby lock them in engagement with the threads 100 on the setting sleeve section 89, and then rotating the mandrel to effect downward feeding of the drive sleeve 77 as previously described. The initial abutment of the upper end face 118 on the sleeve section 89 with the lower face 117 of the cam ring 115 will align the threads 99 and 100 for proper mesh, so that rotation of the mandrel 26 and the drive sleeve 96 will function to feed the setting sleeve 77 and the expander member 54 downwardly, setting the slips 29 and and loading the return spring 110.

An alternative drive sleeve embodiment is illustrated in FIG. 10. In this case the sleeve 120, rather than being longitudinally slotted as previously described, is a rigid cylinder having a plurality ofcircumferentially spaced, rectangularly shaped windows 121 formed in the lower end portion thereof, with each window receiving a threaded insert 122 that is free to move laterally. The rear portion 123 of each insert 122 rides in the groove [01 between the mandrel spline ribs 93, and is held in the outer position where the external threads 99' thereon mesh with the interior threads 100 on the set ting sleeve section 89 when the mandrel 26 is in the lower position within the housing 27. The inserts are permitted to move inwardly to disengaged position, however, when the mandrel 26 is moved upwardly to position the reduced diameter, lower section 94 thereof behind the members. In this alternative embodiment, the threads 99' and 100 do not ratchet past one another during upward movement of the setting sleeve 77 by the coil spring 110, since the inserts 122 may remain in the inner or disengaged positions during such upward movement. In addition, the main body of the sleeve 120 provides a stronger load carrying member than do the fingers 97 during setting of the slips 29 and 30, although the two embodiments are considered to be functional equivalents.

It now will be appreciated that a new and improved sidewall anchor assembly has been disclosed that can be set in response to rotation of the pipe string and released in response to straight upward movement of the pipe. The anchor can be set and released as many times as desired on a single run into the well in a simple and reliable manner. Since certain changes or modifications may be made in the disclosed embodiment without departing from the various inventive concepts involved, it is the aim of the appended claims to cover all such changes and modifications falling within the true spirit and scope of the present invention.

I claim:

1. Apparatus adapted for use in anchoring a well too] in a well bore, comprising: an elongated housing mem ber carrying anchor means that are movable between retracted and extended positions; expander means movable in one longitudinal direction along said housing member for extending said anchor means into anchoring contact with a well bore wall and in the opposite longitudinal direction for enabling retraction of said anchor means; a mandrel coupled to said housing member and movable rotationally and longitudinally with respect thereto; means responsive to rotation of said mandrel for feeding said expander means in said one direction along said housing member to extend said anchor means; means responsive to longitudinal movement of said mandrel for disabling said feeding means and allowing movement of said expander means in said opposite direction; and means operable upon disengagement of said feeding means for automatically shifting said expander means in said opposite direction.

2. The apparatus of claim 1 wherein said feeding means includes a cylindrical member mounted on said mandrel, means on said member movable between inner and outer positions and providing axial cam means cooperable with companion axial cam means on said expander means in said outer position for advancing said expander means along said housing member in said one direction in response to rotation of said man drel.

3. The apparatus of claim 2 further including surface means on said mandrel for locking said axial cam means in engagement with one another during rotation of said mandrel.

4. The apparatus of claim 3 wherein said disabling means comprises releasing surfaces on said mandrel adapted to be positioned adjacent said axial cam means by longitudinal movement of said mandrel and enabling movement of said axial cam means to said inner position disengaged from said companion cam means.

5. The apparatus of claim 4 wherein said axial cam providing means includes a plurality of circumferentially spaced, axially extending fingers on said cylindrical member, each of said fingers being laterally flexible to provide for movement between said inner and outer positions.

6. The apparatus of claim 4 wherein said axial cam providing means comprises segmented nut members carried by said cylindrical member and arranged for radial movement thereon between said inner and outer positions.

7. The apparatus of claim 4 further including means for aligning said axial cam means to mesh with said companion cam means after movement of said expander means in said opposite direction.

8. Apparatus adapted for use in a well bore, comprising: an elongated housing member; normally retracted means movable between retracted and expanded positions with respect to said housing member; expander means movable in one longitudinal direction along said housing member for expanding said normally retracted means and in the opposite longitudinal direction for retracting said normally retracted means; yieldable means continuously urging said expander means in said opposite direction; a mandrel telescopically and rotatably received in said housing and movable between upper and lower positions relative thereto; drive means coupled to said mandrel and responsive to rotation of said mandrel in said lower position for advancing said expander means in said one longitudinal direction; and means responsive to positioning of said mandrel in said upper position for disengaging said drive means to enable said yieldable means to automatically shift said expander means in said opposite longitudinal direction.

9. The apparatus of claim 8 wherein said drive means includes externally threaded means adapted to mesh with internally threaded means on said expander means, said threaded means on said drive means being laterally movable between an outer engaged position and an inner disengaged position.

10. The apparatus of claim 9 wherein said externally threaded means is formed on laterally flexible portions of a sleeve that is corotatively coupled to said mandrel to rotate therewith.

11. The apparatus of claim 9 wherein said externally threaded means is formed by a plurality of circumferentially spaced inserts carried by a sleeve that is corotatively coupled to said mandrel to rotate therewith 12. The apparatus of claim 9 further including first surface means on said mandrel operable in said lower position for locking said threaded means in engagement, and second surface means on said mandrel operable in said upper position for enabling said threaded means on said drive means to move to said inner disengaged position.

13. The apparatus of claim 12 further including means on said expander means and said drive means engageable in said upper position for aligning said threaded means to mesh with one another.

14. The apparatus of claim 13 wherein said aligning means includes axially facing abutting surfaces formed on a helix having the same lead as the threads on said threaded means. 

1. Apparatus adapted for use in anchoring a well tool in a well bore, comprising: an elongated housing member carrying anchor means that are movable between retracted and extended positions; expander means movable in one longitudinal direction along said housing member for extending said anchor means into anchoring contact with a well bore wall and in the opposite longitudinal direction for enabling retraction of said anchor means; a mandrel coupled to said housing member and movable rotationally and longitudinally with respect thereto; means responsive to rotation of said mandrel for feeding said expander means in said one direction along said housing member to extend said anchor means; means responsive to longitudinal movement of said mandrel for disabling said feeding means and allowing movement of said expander means in said opposite direction; and means operable upon disengagement of said feeding means for automatically shifting said expander means in said opposite direction.
 2. The apparatus of claim 1 wherein said feeding means includes a cylindrical member mounted on said mandrel, means on said member movable between inner and outer positions and providing axial cam means cooperable with companion axial cam means on said expander means in said outer position for advancing said expander means along said housing member in said one direction in response to rotation of said mandrel.
 3. The apparatus of claim 2 further including surface means on said mandrel for locking said axial cam means in engagement with one another during rotation of said mandrel.
 4. The apparatus of claim 3 wherein said disabling means comprises releasing surfaces on said mandrel adapted to be positioned adjacent said axial cam means by longitudinal movement of said mandrel and enabling movement of said axial cam means to said inner position disengaged from said companion cam means.
 5. The apparatus of claim 4 wherein said axial cam providing means includes a plurality of circumferentially spaced, axially extending fingers on said cylindrical member, each of said fingers being laterally flexible to provide for movement between said inner and outer positions.
 6. The apparatus of claim 4 wherein said axial cam providing means comprises segmented nut members carried by said cylindrical member and arranged for radial movement thereon between said inner and outer positions.
 7. The apparatus of claim 4 further including means for aligning said axial cam means to mesh with said companion cam means after movement of said expander means in said opposite direction.
 8. Apparatus adapted for use in a well bore, comprising: an elongated housing member; normally retracted means movable between retracted and expanded positions with respEct to said housing member; expander means movable in one longitudinal direction along said housing member for expanding said normally retracted means and in the opposite longitudinal direction for retracting said normally retracted means; yieldable means continuously urging said expander means in said opposite direction; a mandrel telescopically and rotatably received in said housing and movable between upper and lower positions relative thereto; drive means coupled to said mandrel and responsive to rotation of said mandrel in said lower position for advancing said expander means in said one longitudinal direction; and means responsive to positioning of said mandrel in said upper position for disengaging said drive means to enable said yieldable means to automatically shift said expander means in said opposite longitudinal direction.
 9. The apparatus of claim 8 wherein said drive means includes externally threaded means adapted to mesh with internally threaded means on said expander means, said threaded means on said drive means being laterally movable between an outer engaged position and an inner disengaged position.
 10. The apparatus of claim 9 wherein said externally threaded means is formed on laterally flexible portions of a sleeve that is corotatively coupled to said mandrel to rotate therewith.
 11. The apparatus of claim 9 wherein said externally threaded means is formed by a plurality of circumferentially spaced inserts carried by a sleeve that is corotatively coupled to said mandrel to rotate therewith.
 12. The apparatus of claim 9 further including first surface means on said mandrel operable in said lower position for locking said threaded means in engagement, and second surface means on said mandrel operable in said upper position for enabling said threaded means on said drive means to move to said inner disengaged position.
 13. The apparatus of claim 12 further including means on said expander means and said drive means engageable in said upper position for aligning said threaded means to mesh with one another.
 14. The apparatus of claim 13 wherein said aligning means includes axially facing abutting surfaces formed on a helix having the same lead as the threads on said threaded means. 